This invention relates to a method for preparing triorganotin compounds. This invention further relates to a method for preparing a specific class of triorganotin halides in high yield and purity using a method which heretofore has been of limited use, since it was considered operable only for a relatively small group of triorganotin halides.
A general method for preparing triorganotin halides wherein the hydrocarbon groups bonded to the tin atom are (1) cycloalkyl, (2), a combination of cycloalkyl and alkyl or (3) combinations of two groups differing in molecular weight by at least 42 are disclosed in U.S. Pat. Nos. 3,607,891 and 3,789,057. In accordance with this method, a tetraorganotin compound containing two different hydrocarbon groups is reacted with an equimolar amount of a stannic halide. Up until now attempts to apply this method to tetraorganotin compounds other than the types disclosed in the two aforementioned patents have yielded virtually inseparable mixtures of at least two triorganotin halides resulting from nonselective cleavage of the hydrocarbon groups bonded to the tin atom. It has now been found that when the aforementioned tetraorganotin compounds contain three .beta.-substituted phenethyl groups of the general formula ##STR1## and one linear hydrocarbon or phenyl group, the one dissimilar hydrocarbon group is readily cleaved and replaced by a halogen atom when the tetraorganotin compound is reacted with a stannic halide. R.sup.1 in the foregoing formula can be hydrogen or a linear hydrocarbon radical. Surprisingly, the present method is not useful when the methyl group of the foregoing formula and R.sup.1 are both hydrogen.